Fatigue Crack Paths 2003

Fig. 4 Compressive stress σy induced by the compressive load applied on the both edges

of the specimen as shown in the figure. Curves in the figure (b) show the value of σy

when the applied compressive loads induce a 10 000 compressive micro-strain at the strain

gage position shown in the figure (a).

Fig. 5 Values of KII for a single

Fig. 6 Values of KI for a single

edge-cracked plate with a rigid

edge-cracked plate subjected

to bending moment.

grip subjected to shear loading.

plate is made so that the specimen will not be subjected to an unexpected load when

handling the assembly for the following step (iii).

(iii) Then, the completed assembly of frames "A" and "B" and the specimen, which

is clamped by the fixing plate, is mounted on the fatigue testing machine. This mounting is made by tightening the bolts "C" and "D" shown in Fig. 2 to the chucks of the

fatigue testing machine.

(iv) The fixing plate is removed and the test may then start. The observation and

recording of the fatigue crack during mode II cyclic loading are made with a K E Y E N C E

digital microscope (long distance lens VH-W50, controller VH6100). Figure 3 (b)

indicates the positioning and monitoring of the fatigue crack with the digital microscope,

while Figure 7 shows examples of recorded results. The calculation of the stress intensity